Latino adolescents have higher rates of drug use and begin using drugs at an earlier age than other U.S. youth. Given the serious consequences of drug use, it is imperative to identify culturally relevant factors that can enhance the development of efforts to reduce drug use among this population. Familism is a specific type of family connection important to Latino families that implies the children's role in the support and assistance of their family. Recent research suggests that familism is a culturally relevant protective factor against drug use among Latinos, but the mechanisms by which it functions are not well understood. Evidence from developmental neuroscience suggests that risk taking behavior increases during adolescence partly due to changes in the brain's neural circuitry. The cognitive control system, which is involved in self-regulation, develops more slowly relative to the socio-emotional system, which is involved in reward evaluation and sensitivity. This neural imbalance may hinder appropriate evaluation of risk and bias youth towards risky decisions. Familism may function by influencing these neural systems and their correlates to real-life risk taking. The proposed research will utilize a multi-method, longitudinal program of research, including daily diaries and functional magnetic resonance imaging (fMRI), to examine the neural mechanisms by which familism buffers Latino youth from drug use. This study will also examine how neural responses to risk taking predict behavioral changes in drug use behaviors over time. No previous studies have examined the role of culture on the neural correlates of risky behavior. METHOD: Thirty-two Mexican origin adolescents who have no history of drug use will complete a daily diary for two weeks examining their family assistance behaviors. Participants will then come in for an fMRI scan, in which they complete a family assistance and risk taking task. One year later, participants will complete measures of their drug use and risk taking behaviors. Analyses will examine the extent to which individual differences in family assistance (as measured during the daily diary) correlate with increased cognitive control and reduced reward system activity when making risky decisions during the risk taking task. In addition, analyses will examine whether the buffering effects of familism on neural sensitivity to risk taking predict changes in adolescents'real-life risk behaviors including less drug initiation, association with risky friends, sensation seeking, and externalizing behavior. PUBLIC HEALTH RELEVANCE: This research will lead to an increased understanding of how the cognitive control and reward systems relate to familism and real-life drug use and risk taking behaviors. This knowledge has the potential to inform the design of successful interventions that can efficiently target these systems to help reduce drug initiation among Latino youth.